The present invention relates to an apparatus for carrying electrical resistance elements for furnaces. The apparatus is so designed that the elements can be replaced. The device also comprises a block of fibrous, ceramic material which simultaneously supports the resistance element and functions as insulation for the furnace or the like wherein the element is positioned.
Electrical resistance elements are, in some applications, operating at very high temperatures and can then become so soft that they are deformed by their own weight and also are affected by magnetic forces from neighboring elements. The elements are also susceptible to mechanical action, as these types of products are brittle at lower temperatures.
Devices for carrying these kinds of resistance elements are previously known, i.e., by German Pat. No. 1,942,645 and U.S. Pat. No. 4,154,975 and 4,088,825. In the German patent the resistance elements, usually U-shaped or hairpin-shaped, are horizontally insulated and placed upon a number of omega-shaped elements which, in turn, are carried by a carrying element, i.e., a tube of silicon carbide. The carrying element is then fastened on a brick in the furnace wall. To replace an element, the entire carrying device assembly must be removed from the furnace.
The resistance elements may also be serpentine-shaped with two or more shanks, wherein each single shank must be supported. It is important that the furnaces at the high temperatures, up to 1600.degree. C., which may occur, are well insulated. Therefore, many modern furnace designs use insulation made from ceramic fibers, i.e., material marketed under the trademark FIBROTHAL.